German Patent Application DE 4012772 A1 discloses a hammer drill bit for use in rock or concrete, having a cemented-carbide cutting head insert with a cruciform shape comprising four radial cutters and a centering tip protruding above the cutters.
German Patent Application DE 19709771 A1 discloses a drill bit with a one-piece hardened metal cutting head having a main cutter and two secondary cutters, arranged generally in a cruciform shape. The main cutter is such that a complete rotation of the cutting head causes the main cutter to describe a substantially conical surface. The secondary cutters are positioned towards the circumferential edge of the cutting head, and describe a truncated conical surface.
United States Patent Application No. 2005/0274551 A1 discloses a drill bit having a drilling head formed as a hard material body with radial legs and having at least three radially extending cutting bits formed on the radial legs. The drilling head includes a centering tip having concave limiting surfaces stretching between linearly extending auxiliary cutting edges.
The present disclosure seeks to provide improved drill bits and improved cutting heads for drill bits.